1. Field of the Invention
The invention relates to a bore hole packer device provided with resilient seal means expandable against the borehole wall for sealing off and subsequently testing a zone of the formation downhole.
2. Description of the Prior Art
Heretofore, a number of borehole packers for sealing off and pressure testing zones of earth formations require a source of air or gas pressure at and a conduit from the surface to expand or inflate a resilient bladder or seal against the bore hole wall. Others, disclosed in U.S. Pat. Nos. 2,854,080, 3,646,995 and 3,741,305, require a pipe string extending from the surface and connected to an inner telescoping mandrel to mechanically position, activate and retrieve the packer device. Setting of the packer is attained by force applied to the inner pipe string which axially shift expander sleeves, cones, or slips, to compress and/or expand resilient means into sealing engagement with the casing or borehole wall.
A similar packer disclosed in U.S. Pat. No. 2,691,418 utilizes a resilient cup like seal including toothed slips for engaging a casing or bore hole wall. The packer is lowered to and retrieved from a site downhole by a pipe string attached to an inner fluid conduit coupled to the cup seal retaining sleeve by a pin projecting into a J-slot in the sleeve. Rotating the pin from the J-slot allows the fluid conduit and attached valve head to be raised into sealing engagement with a valve seat on the retaining sleeve and thus prevent escape of fluid under pressure passed through the conduit, expand the cup seal, seal off a lower zone of the bore hole and test the adjacent formation.
Unlike prior art packers the applicant's device is used in combination with a core drill bit or like sub attached to the lower end of a drill string casing and raised to the desired site above the bottom of the bore hole after taking a core sample of the formation.
The device is lowered into and retrieved from the drill string by a conventional wireline and latch mechanism attached to an inner telescopic hollow mandrel and housing. A resilient cup seal attached to the lower end of the mandrel is initially contracted and retained within an end chamber of a housing which upon being arrested by an internal shoulder of the drill bit causes continued relative downward movement of the mandrel to eject the cup seal from the end chamber, and allow expansion thereof against the bore hole wall. Fluid can then be pumped directly down through the drill string and inner mandrel to test the formation below.